Carboxylated derivatives of oleyl alcohol and method for their production



United States Patent C it OXYLATED DERIVATIVES F ULEYL ALCO- HOL AND hIETHOD FOR THEIR PRODUCTION Edward T. Roe, Chalfont, and Daniel Swern,Philadelphia,

Pa, assignors to the United States of America as represented by theSecretary of Agriculture No Drawing. Original application June 20, 1960,Ser. No. 37,533. Divided and this application Jan. 22, 1962, Ser. No.176,473

4 Claims. (Cl. 260-413) (Granted under Title 35, US. Code (1952), see.266) A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with power to grant sublicenses for such purposes, ishereby granted to the Government of the United States of America.

This application is a division of SN. 37,533, filed June 20, 1960, nowabandoned.

This invention relates to carboxylation of long chain unsaturated fattycompounds and has among its objects the carboxylation of long carbonchain olefinic compounds with carbon monoxide at atmospheric pressure.

In accordance with this invention, direct carboxylation of long chainolefinic compounds with carbon monoxide can be achieved at atmosphericpressure by employing a narrow range of operating conditions in, whichthe concentration of the sulfuric acid and also the molar ratio ofsulfuric acid to the long chain olefinic compound must be regulated.

According to the present process carbon monoxide at atmospheric pressureis (a) dispersed in aqueous sulfuric acid having a concentration in therange of about 93 to 98% H 80 (b) the olefinic compound is combined withthis sulfuric acid at about 20 C. in such proportions that the resultingmixture contains at least about three moles water to each mole ofolefinic compound, and (c) during the mixing of olefinic compound andsulfuric acid additional carbon monoxide is dispersed in the mixture.The entire operation is conducted at substantially atmospheric pressure,and the new carboxylic acid derivative is recovered from the sulfuricacid by dilution with water and solvent extraction or mechanicalseparation.

The product is typically recovered from the reaction mixture by pouringthe sulfuric acid solution into a mix: ture of ice and water, followedby extraction of the product with a suitable solvent such as ether.Alternatively, procedures for extracting the product directly from thereaction mixture may be employed.

A critical variable in the high yield atmospheric carboxylation of theless reactive, long carbon chain nonterminally unsaturated compounds isthe concentration and quality of water. The importance of water is quiteevident, as shown in Table I, in which the results of the carboxylationof oleic acid are tabulated. In all of these examples the amount ofwater does not change during carboxylation, since the carbon monoxide isgenerated externally. The following equation summarizes the chem--(wherein 1 may be 6 to 9) Commercial oleic acid was purified bycrystallization at low temperature followed by fractional distillationto give the oleic acid employed as the starting material in theseexamples.

The present invention is illustrated with particular reference toExample 6 (Table I):

Carbon monoxide was passed through 80.4 g. (0.795 mole) of 97.2%sulfuric acid contained in a SOD-ml. three-neck flask, vented to theatmosphere, using a gas dispersion tube with a coarse fritted cylinder.With stirring, 7.1 g. (0.025 mole) of oleic acid was added dropwise in16 minutes to the sulfuric acid solution which was saturated with carbonmonoxide. Carbon monoxide was allowed to pass through the stirredmixture for a total of two hours, while the temperature was maintainedbetween 9 and 13 C. with external cooling. At the end of this time themixture was poured into approximately 300 ml. of a mixture of ice andwater. The product was extracted with ether and washed free of sulfuricacid. The ether solution was dried over anhydrous sodium sulfate,filtered, and the ether was then evaporated, yielding 6.4 g. of paleyellow syrupy material having an iodine number of 12.9, acid number,300, and saponification number, 300.

The reaction conditions for the other examples were the same asdescribed for Example 6 with the exceptions listed in Table I,specifically, mole ratio of sulfuric acid to oleic acid, concentrationof sulfuric acid, and time of stirring the mixture. 1 7

TABLE I.REACTION OF OLEIC ACID WITH GASEOUS CARBON MONOXIDE Mole RatioSnliuric Ex. acid, Time, Acid Iodine No. Oleic Sulperhrs. Number bNumber acid iuric Water cent acid 1 5. 5 3.0 91 2 a 150 18 1 9. 6 1. 597 2 222 1 9. 6 1. 5 97 6 226 1 18. 0 2. 8 97 1 252 34 1 19. l 3. 0 97 2287 20 1 31. 8 5. O 97 2 300 13 1 63. 6 10. 0 97 2 297 16 1 24. 0 0 1002 d 215 63 Water present in sulfuric acid.

Saponification number essentially the same as acid number, except wheregiven below.

0 Saponification number 201.

d Saponification number 251.

Referring to Examples 1 to 8, the extent of carboxylation is indicatedby an increase in acid number and adecrease in iodine number. With 91%sulfuric acid (Example 1) no carboxylation takes place. The acid numberactually indicates a loss of carboxyl group. Since the same mole ratioof water, three moles of water to one mole of oleic acid, when containedin a more concentrated sulfuric acid (Example 5) is adequate, one mustconclude that 91% sulfuric acid istoo dilute for this process. i

0n the other hand, 1.5 mole of water per mole of oleic acid isinsufficient for caboxylation to proceed in a satis factory manner(Examples 2 and 3) even though the con centration of sulfuric acid is97% and the reaction time is extended to six hours. With 100% sulfuricacid (Example 8) carboxylation, if occurring, is negligible, showingconclusively that water must be present during the reaction.

The greatest increase in acid number and decrease in iodine number,indicating maximum carboxylation, is obtained when five moles of waterper mole of oleic acid is employed (Example 6.) Increasing the amount ofwater above five moles per mole of oleic acid (Example 7) or increasingthe reaction time beyond two hours does not increase the amount ofcarboxylation.

The product obtained by the carboxylation of oleic acid, the pale yellowviscous liquid described in Example 6, could not be purified by lowtemperature solvent crystallization, but distilled readily atabout 200C. and 0.45 mm. mercury pressure to give a product having an acid numberof 341, carbon and hydrogen analyses of 69.4 and 11.7%, respectively,and molecular refractivity of 92.8. These and other data obtained forthe product are included in Table III. Infrared spectra and gaschromatographic analyses of the product were also obtained. All the datasubstantiate the conclusion that the product is canboxystearic acid ofthe Formula I.

In a major portion of the product, the carboxyl group in probably in the9 or 10 position (x=7 or 8) However, in view of the nature of strongacid-catalyzed double bond addition reactions, the 8 and 11 isomers (x=6or 9) are product obtained by carboxylation of oleyl alcohol into an iceand water mixture, it was necessary to hydrolyze the sulfate ester byboiling. Otherwise the procedure was substantially that employed inExample 6.

Table II shows the high recovery of typical crude reaction products andthe extent .to which they are carboxylated by comparing the acid numberof the product with that calculated.

TABLE II.-CHARACTERISTICS OF CRUDE the acid number; with methylr-icinolcate and linoleic acid, however, the saponification number isquite diiferent from the acid number. This suggests that an ester orlactone has formed in the latter two instances. Also, the hydroxyl valueof the product obtained from methyl ricinolcate is much lower than wouldbe expected. The significance of these points will be discussed later inmore detail.

In all of the preparations except that of the oleic acid derivative, itwas desirable to convert the crude reaction products to methyl estersbefore purification by distillation.

The usual method of direct esterification does not completely esterifythe branched carboxyl group. Using dimethyl sulfate, as illustrated inthe following example, nearly complete esterification is obtained after42 hours reflux.

Example 13.--Preparati0n 0 the dimethyl ester of carboxystearic acid Adistilled fraction from the product of carboxylation of oleic acid wasused as starting material. This fraction had an acid number of 325,therefore consisting mainly of carboxystearic acid. The fraction, 13.8grams, was combined with 68 ml. of anhydrous methanol and 5.3 grams (3.9ml.) of dimethyl sulfate and heated at reflux temperature for 42 hours.The product was worked up by neutralizing the dimethyl sulfate withaqueous sodium carbonate solution in the cold and extracting with ether.(In larger preparations, from one half to two thirds of the alcohol wasdistilled off before neutralization and dilution, thus increasing theefiiciency of the ether extraction.) Distillation of 9.4 grams of themethyl esters from an alembic flask yielded 5.8 grams of a clear, mobileamber liquid, B.P. 146-148" C. (0.35 mm.), 11 1.4465.

Analysis.Calcd. for C I-1 0 C, 70.7; H, 11.3; molar refractivity, 102.8.Found: C, 70.6; H, 11.3; molar refractivity, 102.6.

From the chemical analyses, infrared spectra, and gasliquidchromatography showing several closely related major components it isconcluded that the product is a mixture of insomers which would beexpected from esterification of the product of Formula 1.

Methyl esters of carboxyoctadecanol, carboxylated methyl ricinoleate andcarboxylated linoleic acid (Examples 15 to 17, respectively) wereprepared in a manner similar to that described for esterification ofcarboxystearic acid. Esterification of these other branched chaincarboxylic acids also takes a long time. The long time REACTION PRODUCTSAcid N o. Sapon. N o. Iodine No. Percent Hydroxyl Example No. StartingMaterial lgeld,

Calcd. Found Calcd. Found Calcd. Found Calcd. Found Oleic acid 32 342297 342 305 0 2 Oleyl alcohol 33 178 135 178 138 O 5 5. 4 4. 8 Methylricin0leate 29 157 b 217 313 319 0 19 4. 7 1. 4 Linoleic acid 32 344 c275 344 306 78 48 I Yield based on 30 gms. of starting materials.Calculated values are for:

CH3 (CH1) rflJH-(OH X-CH-(CH:) yCOOCH OH O O OH (x-l-y=9) High acidnumber is probably due to partial hydrolysis of methyl group.

0 Calculated values are for:

CH;(CH) CH=CH (CH1) r-CH-(CHz) y 'CO0H The reduction of the iodinenumber from that of the starting material also indicates the extent ofthe reaction. The saponification number of the products obtained fromrequired for complete esterification provides chemical evidence for abranched carboxyl group, as it is well known that such structures behavein this way. Characteristics oleic acid and oleyl alcohol areessentially the same as of these methyl esters are presentedinTable 111.

TABLE LIL-CHARACTERISTICS OF PURIFIED PRODUCTS Boiling Point Carbon,Percent Hydrogen, Percent Refrac- Ex. Compound m (1 Molecular tion N0.calcd. Found 0. mm. Galcd. Found Calcd. Found 9- Carboxystearic acid200-201 0. 45 69. 5 69. 4 11. 1 11. 7 1. 4615 0. 9726 93. 5 92. 8 13.Din flthyl ester of carboxystearic 146-148 0.35 70.7 70.6 11.3 11.31.4465 0.9281 102.8 102.6

acr 14- Dibuyl ester of carboxystearie 183-185 0.40 73.6 73.4 11.6 11.81.4465 0.9033 130.6 130.1

aci 15 Methyl ester of carboxyoetade- 153-155 0.45 73.1 73.0 12.312.3 1. 4535 0.9095 98.0 97.7

cane 16.-." Methyl ester of carboxylated me- 161-162 0.40 70. 6 69.210.7 10.7 1.4530 0.9628 96.0 95.6

thyl 1101110183138. 17 Methyl ester of carboxylated 160-161 0.40 70.668.7 10. 7 10.7 1. 4530 0.9699 96.0 94.9

linoleic acid.=

Percent 0, percent H and molecular refraction calculated for CHq(CHn)(|JH(CHz):CH(OH,),COOCH;

(x+y=9; x probably-=1 or 2) The di-n-butyl ester of carboxystearic acidwas prepared either by direct esterification or by ester interchangefrom the dimethyl ester. In direct esterification, it was necessary toelevate the boiling point in order to obtain complete reaction. Cymenewas used for this purpose, but it made the recovery of the productdiflicult.

Example 14 The ester interchange reaction was carried out in thefollowing way. To 33.5 g. of methyl esters (acid number 6.3) preparedfrom crude carboxystearic acid (acid number 310) was added 142 ml. ofn-butanol with which 0.42 g. of metallic sodium had been reacted, andthe mixture refluxed for hours. In order to determine when theinterchange was complete, the methanol evolved was removed and measured.For this purpose a 1 x 20" fractioning column packed with Raschig ringswas used. The product was worked up by pouring the reaction mixture intodilute hydrochloric acid and extracting with ether. After washing theether layer free of acid it was dried over sodium sulfate, filtered, andthe ether was then evaporated, yielding 40.9 g. of crude dibutyl estershaving an acid number of 10.7. The acidity of the crude dibutyl esterswas neutralized with potassium hydroxide, and the product was vacuumdistilled.

The distilled dibutyl esters of carboxystearic acid obtained by the twomethods of prepartion had the same properties cf. (Table III.)

Neither the methyl or butyl ester could be completely hydrolyzed byrefluxing with dilute alcoholic potassium hydroxide for eight hours.This is additional chemical confirmation of a branched carboxylic estergroup.

While not illustrated by specific examples it is readily apparent thatother esters can be prepared by employing ethanol, propanol, or otherhigher boiling alkanols in the procedure of Example 14 in place ofbutanol.

The structural similarity among the methyl esters of the carboxylatedproducts was very marked when the infrared spectra were compared.Confirmation of side chain carboxylation is present in all instances,and on the basis of further infrared spectra evidence, carboxylation ofoleyl alcohol according to the present invention, followed byesterification, gives a product of the Formula II COOR wherein x is 6 to9 and R is an alkyl group.

The apparent anomaly shown in Table II and III in respect to thestructure of the product obtained by carboxylation of methyl ricinoleateis clarified by study of analytical data and infrared spectra of methylesters, leading to the conclusion that the crude reaction product is amixture of CEL -(CH h-(fiH-(CHz)x-CH--(CHz)yCOOCHa 0H OOH and3(CHz)5-CH(CH2)xCH(CH2)y COOCH3 r' ';=0 wherein the sum of x and y is 9and x is 1 or 2.

The unsaturation still present in the crude carboxylated linoleic acidacid is not due to unreacted linoleic acid, as shown by alkalineisomerization. The ultraviolet absorption spectrum of the isomerized andunisomerized samples are the same. The unsaturation, therefore, must bein an unsaturated dicarboxylic acid.

A comparison of the chemical and physical data obtained on the distilledmethyl esters of carboxylated linoleic acid with those of the distilledmethyl esters of carboxylated methyl ricinoleate (Table III) shows aclose similarity. The infrared spectra of the two products areessentially identical. The methyl esters of carboxylated methylricinoleate and of linoleic acid are, therefore, identical and may berepresented by the Formula III a( H2)a- H(CHz) x-CH-(CHz) y-C 0 0 CH =0III wherein the sum of x and y is 9 and x is 1 or 2.

The carboxylation of long carbon chain olefinic compounds according tothe present invention enhances their functional properties for use inthe manufacture of alkyd resins, polyesters and polyamides and otherpolymer applications, or when fully esterified, they can be used asplasticizers or functional fluids such as synthetic lubricants andhydraulic fluids.

We claim:

1. A process for introducing a carboxyl group into oleyl alcoholcomprising dispersing carbon monoxide, at substant'ially atmosphericpressure, in sulfuric acid containing about from 2 to 7% water,combining calculated amounts of oleyl alcohol and said sulfuric acid toprovide a liquid phase having a ratio of at least about 3 moles of waterto 1 mole of oleyl alcohol, and, at a temperature of about from 10 to 20C., contacting the oleyl alcohol in liquid phase with carbon monoxide atabout atmospheric pressure to introduce a carboxyl group at the doublebond of the oleyl alcohol, and separating the carboxylic acid derivativefrom the reaction mixture.

2. A compound having the formula wherein x is an integer from 6 to 9.

3. The compound of claim 2 wherein at is 7. 4. The compound of claim 2wherein x is 8.

References Cited by the Examiner UNITED STATES PATENTS 2,831,877 4/58Koch 260-413 2,911,422 11/59 Ercoli 260-413 3,047,622 7/ 62 Kurhajec eta1. 260-413 CHARLES B. PARKER, Primary Examiner.

ABRAHAM H. WINKELSTEIN, Examiner.

1. A PROCESS FOR INTRODUCING A CARBOXYL GROUP INTO OLEYL ALCOHOLCOMPRISING DISPERSING CARBON MONOXIDE, AT SUBSTANTIALLY ATAMOSPHERICPRESSURE, IN SULFURIC ACID CONTAINING ABOUT FROM 2 TO 7% WATER,COMBINING CALCULATED AMOUNTS OF OLEYL ALCOHOL AND SAID SULFURIC ACID TOPROVIDE A LIQUID PHASE HAVING A RATIO OF AT LEAST ABOUT 3 MOLES OF WATERTO 1 MOLE OF OLEYL ALCOHOL, AND, AT A TEMPERATURE OF ABOUT FROM 10 TO20*C., CONTACTING THE OLEYL ALCOHOL IN LIQUID PHASE WITH CARBON MONOXIDEAT ABOUT ATMOSPHERIC PRESSURE TO INTRODUCE A CARBOXYL GROUP AT THEDOUBLE BOND OF THE OLEYL ALCOHOL, AND SEPARATING THE CARBOXYLIC ACIDDERIVATIVE FROM THE REACTION MIXTURE.
 2. A COMPOUND HAVING THE FORMULA